Unit 4.3 – Comminution and Mixing Equipment

Crushing is the first step in:

• Heat transfer

• Size reduction

• Distillation

• Liquid mixing

Grinding is used when the process requires:

• Larger lumps

• Fine-sized powders

• Increased viscosity

• Dehydration

Crushing design is considered primarily:

• Theoretical

• Empirical

• Chemical

• Magnetic

Equipment selection for comminution relies heavily on:

• Chemical reaction rate

• Experience and manufacturer advice

• Ambient humidity

• Tank geometry

Key factors for selecting crushing and grinding equipment include all EXCEPT:

• Feed size and required product size distribution

• Throughput

• Material hardness and abrasiveness

• Color of the feed

When evaluating material properties for comminution, engineers consider:

• Density, toxicity, flammability, stickiness

• Boiling point only

• Electrical conductivity

• Magnetic susceptibility only

Wet grinding must be assessed to determine:

• If it is permissible

• The vapor pressure

• The freezing point

• The flame temperature

Mixing of solids, liquids, and gases is essential in:

• Only final blending

• Nearly all stages of chemical production

• Only separation units

• Only laboratory work

Mixing is often combined with other operations such as:

• Refrigeration only

• Reaction and heat transfer

• Filtration

• Drying only

Many liquid and solid mixing operations are carried out as:

• Continuous processes exclusively

• Batch processes

• Vacuum distillations

• Electrochemical steps